Furnace construction



Jan. 29, 1 935. J. c. CAMERON El AL 1,989,400

Y FURNACE CONSTRUCTION Filed July 1, 1931 2 Sheets-Sheet 1 INVENTORS Jfin C 6411281072 CfCFOulland 2065f QM MM) YATTQRNIZY Jan. 29, 1935.

J. c. CAMERON El AL 1,989,400

FURNACE CONSTRUCTION Filed July 1, 1931 2 Sheets-Sheet 2 Ha Ho 0 24 1' l0 INVENTORS I J/m CUE-maven f CfTPouJ/Qnd 2.47:5?

ATTORNEY Patented Jan. 29, 1935 umTEDfs'TATEs FUanijifc oonsrn o'rIoN John C. Cameron and -Charles E.- R; West, I

;:"'=Detroit, Mich. implicatio -July 1, 1931, serial iNo. 548,158 reclaims. (c1. 158--1 This invention relates to heating systems :;-for buildings and-it has particularrelation tothat type of system in which heat is generatedina furnace at a point relatively-remotewfromg the 5 zone which is to be heated-and isthen conducted to the latter point through the agency ofaJfi-uid conduction agency which absorbs heat from the furnace and then releases it at the pointwhere itistobeused,

vision of a furnace structure in ,WhiQh a minie mum amount of air is sufiicient to oxidize the fuel and thus to render its heat energyavailable, thus obviating, the heating of excessive volumes of air in the combustion chamber; the provision of a furnace structure which is adapted toiabsorb considerable proportions of-the heat present in the combustion gases that normally escape through the furnace stacks and then release this heat to the furnace walls; the provision of a furnace structure embodying means fonpreventing the escape of absorbed heat from the interior of thefire'box. through convection while the --furnace burner is inoperativeythe provision of a furnace structure embodying meansfor simul: taneously rendering the burner inoperativeand for sealing the fire boxof the furnace against convection losses. v

The conventional furnace as. ordinarily constructed embodies an inner shell or fire box and .an outer shell or casing which provides a chamber about the fire box through whicha convection medium such as air orwatermay be circulated for purposes of transferringheat from the; walls 35 of the fire box to therooms or buildings .-vvhich are to be heated. The walls of the furnacemay be supplied with heat by means ofa suitable burner disposed in the fiIQbQXQIIId which may be fed with fluid fuelsuohas-fuel oilor gas. In

40 these conventionaltypes of furnace the-chamber constituting-the fire box is substantially unobstructed and mixtures of fuel and air together with the combustion gases generated. therefrom flow with but slight turbulence directly through the fire box and out at the chimney. As aresult, interaction between the fueland oxygen; of the air to generate'heat takes *placeat arelatively low rate and the amount of radiant:heat liberated thereby to -the furnacewalls iscomparatively low. It will also be apparent that such structures complete combustion does not take place until the mixture of fueland 'air'has progressed a considerable. distance throughthe fire box and into the stacks. As a, result, the temperatures of the combustion gases'in the lower The invention has for its main objects and intermediate zonesof the furnace are cornparatively low .while the temperatures at the zone adjacentto the stack are comparatively hi h:- Under such conditions the combustion gases when under optimum conditions for transferring heat i to the furnace walls are. in contact withthe latter only for a comparatively short iperiod of time. Consequently, onlya small} portion of -the total heat generated'bythe combustion gases is transmitted to the walls of the furnace-andfrom the latter to the convectionmedium employedfor conveying heat .to' the buildings which are tobe heated.

Furthermore, in the conventional type-.offurnace structure, the walls of the'fire box. are comparatively thin and "as: a result they are very quickly heated-to relatively high temperatures. However, since the mass of the walls is relatively low the total amount of heat absorbed is-also quite low. Therefore, when the temperature of v the room has been raised to a. desired point and the burner is shut down the heat contained in the furnace walls is soon dissipated-to the convection medium and inorder to maintain the temperature, operation of the burner mustsoon be reinitiated. These undesirable conditions are intensified-by reason of the factthat much of the heat absorbed by the furnace walls and; on trapped in the combustion gases within the fur nace when the burner, is. closed down is P8 mitted' to escapedirectly up the stacks by reason of convection and is:not absorbed .by the walls and then re-transferred to the convection medium in the outer chamber.

This invention contemplatesthe provision of a furnace structure in which'these various unde sirable effects are overcome by theprovision of a foraminous checkerworklike structure in the firebox of the furnace adapted to throw the mixe ture of fuel and air into violent. turbulence and thus obtain substantially complete combustion of mixture at very high temperatures inthe lower zones of the furnace, the structure, further-being adapted to act as a baffle to prevent" the direct flow of. gases within the fire box through the z stack. The invention also includes a; damper structure operated in synchronism with. the burner'structure for substantially completely clo'sing the stack-passage when the burner-is in.-

operative and thus preventing convection losses of the heat' contained in the products of combus'ftion which may remain in the furnace and also preventing loss' 'through the stack ofjheatunits absorbed in "the foramino referred. to.

us, structure previously Fig. 4 is a cross-sectional view of a heater coil adapted to be employed in connection with my improved furnace structurefor, purposes ofsupplying hot water for domestic use.

Fig. 5 is a diagrammatical view of a furnace structure and the electrical wiring employed for controlling the operation thereof.

Fig. 6 is a fragmentary cross-sectional view disclosing a slightly modified type of burner structure which may be employed in combination with the baiile structure constituting a portion of" the subject matter of the present invention. a Fig. '7 is a fragmentary cross sectional view of adamper which may be employed in the stack of the furnace constructed in accordance with the provisions of the l present invention," taken on line 7-7' of Fig. 8. 1

Fig. 8 is a fragmentary view partially in crosssection and partially in elevation of the damper construction disclosed in Fig. 'l.

Thefeaturesconstituting the subject matter of the present invention may be employed incombination with a furnace 10 of conventional design embodying an outer shell or jacket 11 and an inner shell or jacket 12 between which a space 14 for a convection medium such as water is defined. The inner of these jackets which constitutes a fire box is also so formed as to provide a water head 16 and a steam head 18 through which fines 20 and 22 leading to a stack 24 respectiyely' extend. Conventional pipes (not shown) lead from the steam head 18 to a room 28 indicated conventionally in Fig. 5.

The above described furnace structure is supported upon a base 30 having an inwardly directed flange 32 which supports a baifie structure constituting an important element of the present invention and which is to be later described. A burner 34 for fluid fuel is disposed approximately centrally of the base 30 and is adapted to discharge a burning mixture of air and oil outwardly and upwardly into the fire box defined by the walls 12. Fuel oil and air may conveniently be suppliedto the burner by means of a conduit 38. Since the structure of the burner is conventional it is not deemed necessary to describe it in detail. It is deemed sufficient to state that fuel and air under the desired degree of pressure is fedthereto through the conduit 36 by means of a motor driven pump structure indicated at 38 in Fig. 5.

The bai'fle or checkerwork construction constituting an important element of the invention comprises a series of upwardly and radially inclined supports 40 of heat resistant material such as cast iron, having feet 42 at their lower end which rest upon thefiang'e 32 and which if desired may be secured in position by asuitable heat resistant cement, not shown. The supports areconilned from radial outward displacement by means of a. ring 44 surrounding the standards 40 in a plane intermediate the ends thereof and engaging shoulders 46 formed on the outer edges thereof. At their upper ends the standards 40 are slotted as indicated at 47 to receive the outer edge of a circular baffle plate 48, which is adapted to support and thus prevent inward displacement of the upper ends of the supports. In order to protect this baflie plate from excessive heat, a flame guard 50 is secured to the lower surface thereof by means of screws 52 best shown in Fig. 4.

The checkerwork structure includes a base ring 54 composed of segments 55 which as shown in Fig. 1 are of inverted trapezoidal cross sectional contour- A cylindrical ring 58 is disposed adjacent to the inner periphery of the wall 12 and rests at its lower edge upon the upper face of the base ring 54.

The upper faces of the rings 44 and 58 respectively support the inner and outer ends of a series of laterally spaced fire bricks 60 of trapezoidal elevational contour which are disposed in radial relation with respect to the inner walls of the furnace in much the same manner as the bricks 66 shown best inFig. 2 and more'fully described later. These bricks in turn support a pair of concentrically disposed spaced rings 62 and 64 which, a

like the ring 54 previously referred to, are composed of a plurality of segments. The rings in turn support a series of radially arranged bricks 66 which, as shown in Fig. 2, when viewed from above are of substantially trapezoidal contour. These bricks, as shown in Fig. 1, are notched at 68 and the ends thereof rest upon the upper extremities of the supports 40. In order to supplement the checker work action produced by this series of bricks a second series of bricks '70 which former of which, like the bricks 66, are of traps-- zoidal cross-sectional contour and the latter of which, like the bricks 70, are substantially rectangular. These bricks preferably are arranged instaggered relation with'respect to the bricks 66 and 70 in order more effectively to deflect the gases in their upward flow through the furnace.

A damper structure preferably is disposed in the stack 24 and may, asshown in Figs. '7 and 8, include a pair of concentrically disposed cylinders 82 and 84 which are disposed transversely of the stack and which respectively include slots 86 and 88 which may be brought into alignment with each other or disposed in staggered relation depending upon the desired operation of the furnace whereby selectively to permit the flow of combustion gases to the stacks or to interrupt the flow in accordance with the temperature existing in the room or building 28. The cylinder 84 preferably isnon-rotatably secured in the flue or stack as by welding along diametrically opposite points of tangency and the cylinder 82 is rotatably mounted therein upon transversely extending bars 90 which are rigidly fixed upon stub shafts 92 and 94. These shafts are 'journaled in bearings 96 and 98 in the side of the stack.

For purposes of rotating the cylinder 82 and thus bringing the slots 86 and 88 into and out of register with respect to each other, a lever or arm 100 is rigidly secured'to the shaft 94 and the lower end thereof is pivoted to apiston rod 102. that may constitute a'. reciprocable. armature within a solenoid'coil. 104 of conventional construction. This solenoid is provided with attach, ing lugs 106 which are secured to the side of the stack 24 by. means ofjbolts 108. Energizing current issupplied. to the solenoid by means of conductors 110. and 112. When the solenoid is deenergized,'the rod 102isheld in retracted position bymeans of a coiled spring 113 secured to the side of the flue 24.

Asbest shownin Fig.- 5,-the'winding-of solenoid 104 is connected in series with a thermostatically controlled--switch-116, disposed in room 28, and'iscut into one line 118 of the current supply line-for the driving motorofthepump-BS. Thus,-one Supply; line isconnected to one'side of a winding of the motor for pump 38, the other line-118- connected to one side of switch 116, a conductor 112 connects the other side of switch 116 to one terminal pf the winding of solenoid 104, and conductor' llquconnects the. other terminal of winding of solenoid-}104 to thegother side of the winding of.the driving motor for the pump 38. The operation .otthe abovedescribed structure maybe outlined asfollows: It will be assumedthat the temperatureof the room 28 is below a p're-. determined value andthat the supply pump 38 is either operating at afvery .low'rate of speed or else is entirely 'stop'ped'and the dainpnstructure is .closed. Underthese conditions the/switch 116 will move toclosed position thus closing the circult of themotor '3'8and energizing the solenoid 104 to rotate-the. cylinder 82 .in such manner as to bring the slots 86 and- 88 into register with each other; thus establishing .a draft throughthe furnace. Under these conditions the burner 34 will operate at'full force andthe flames therefrom will be directed upwardly and outwardly over the lip of the ring 54 and into the various passageways provided in'the checkerwork disposed within the fire box 12. The variousunits constituting the checkerwork will break upthe flow of the mixture offuel and. air. and'as' a' result the latter will be thrown 'into comparatively violent agitation or turbulence, thus thoroughly intermixing the fuel and the air and insuring immediate and complete combustion of the mixture in the'lower zones of the furnace. Obviously, a portion of the heat thus generatedwill be radiated immediately to the walls of the furnace, while a portion will be absorbed by the 'checkerwork'as the mixture flows upwardly through the latter. By reasonof the fact that combustion takes place more completely 'in" the lower zones of the furnace than in the conventional structure it will be apparent that the gases attheir maximum temperatures will.,be =maintained in the furnace for amuch longer periodthan in the conventional construction and accordingly a higher percentage of. heat is absorbed from theburnt gases than inthe ordinary furnaces'. The checkerwork which includes the baffle. plate48 as anelement also extends completely across thestream of gases as it flows upwardly throughthe' furnace and as a result, much heat contained in the central zone, which ordinarily would pass out through the stack, is absorbed. This heat is released to the wall 12 and is thus made available to the convection medium in the chamber 14. After the temperature of the furnace has been raised sufliciently to cause the elevation of the temperature of the room 28 to the desired point, the switch 116 will open and as a result the solenoid 104 will be deenergized and the burner 34 will shut down. Deenergization of the solenoid 104 allows spring 113 to irotatethe cylinderr 82 ,to. bring the slots 86 and Y88 into staggered relationthus closing the. stack of the furnace; In'order-to prevent the development of pressure-within the fire box 12 which might result. inthe expulsion of highly heated gases from the furnace into the room in which the furnace is disposed a bleeder bypass including a conduit: 122 having openings 124 and 126 disposed upon. opposite sides of the damper structure, is connected to the flue;24. The size of this bypassofcourseis such that-only relatively small volumes, of gases can pass up the stack. Under these conditions, convection of heat absorbed by the checkerwork and the furnace wall is substantially :prevented. .As' a result all of the heat absorbed in the latter elements is radiated .to the convection medium 1 contained in the chamber 14 and from the latter is conducted intothe room. 28. ;Byreason ,of the; relatively great quantity of heat absorbed in the system and the. prevention of the convection thereof through. the-sides,.-the room is maintained at a substantiallyuniform temperature over a relatively long period of time without the operation ofv the burner 34. H Anadditional'economy of fuel is thuspbtained.

In Fig. 6 is disclosed a slightly modified form of our invention-which is. adaptedforquse ofa burner 130 of the spinner .type which includes a rotor 132 driven byamotor 134. Fueloil may be supplied to the rotor through a passage, (not shown) formed in the rotor shaft 136 or in any other convenientmanner. The oil is discharged outwardly between a series of vanes 138 provided upon the upp r surface of the rotor. An annular disc 140 is diposed-about therotor andis supported upon flange 32to prevent the passage of fuel and air downwardly into the base of the furnace structure. The upper margin of this disc 140 is provided withla. ring member 142 comprising upwardly. extending flanges-144and 146. These flanges 'are'formed with slots148 that function more effectively to intermingle the fuel and the air as they are thrown bycentrifugal force from the rotor 130.. The checkerwork including feet 42 rests directly upon theseflanges. The operation' of this embodiment'of the invention is substantially similar to thatdisclosed in the previously described figures,

In Fig. 4 is disclosed awater heater structure which may conveniently be employed in combination with .theprevijously described checkerwork and it is highly desirable where the invention is used in combinationwith furnaces" employing air as a convectionmedium. This heater structure includes inner and outer ,coils 150 and 152 which are connected with each otherin conventional manner and which also are connected to inlet and out1et1 c0nduits156 and158. These coils preferably are disposed directly above the bafiie plate '48 and may be' disposed'within the circumferencecf the ring 72 disclosed in Fig. 1. It 'willthus'be apparent that 'we 'have, provided a'simplea'ndconvenient structurefor use in connection with conventional furnaces the use of which results in the more efiicient burning of fuel and the more effective transfer of heat of combustion products to the convection medium. The construction is economical to produce and may be employed in combination with substantially any of the standard furnaces. By the use of the refractory checkerwork described a more complete burning of the fuel is obtained, a more compact structure is provided than in structures heretofore provided without materially restricting the free flow of gases. therethrough; and a more eflicient absorption of the heat by therefractory results without disadvantageously affecting the desired heat transmitting effects di rectly from thegases to the surrounding walls of the chamber as in constructions previously suggested.

Although we have described and illustrated only the preferred embodiments of'the invention, it is to be understood thatthe latter is not so limited but that'various modifications may be made therein without departure from the spirit of the appended claims. 1

We claim:

' w l. A furnace checkerwork comprising a plurality of vertically spaced refractory rings, a plurality of spaced refractory blocks interposed between adjacent rings, and means forsupporting said rings and blocks to form a conical cham ber therein. '1' 1 2. A furnace checkerwork comprising a; plurality of series of refractory rings disposedin vertically spaced planes, spaced refractory bricks disposed between each said series a-nd that one of said series next above it, said rings and bricks defining a conical chamber therein, and means for supporting said rings and'bricks- 3. A furnace checkerwork comprising a plurality of series of refractory rings disposed in vertically spaced planes, spaced refractory bricks disposed between each said series and that one of said series next above it, said rings and bricks defining a conical chamber therein, inwardly and upwardly inclined supports in said chamber for said bricks, anda transversely disposed baffle plate disposed at the upper ends of said supports. 4. For use between theinlet and the outlet of a furnace, an open checkerwork of refractory material forming a conically shaped chamber therein, a standard in said chamber comprising a plurality of legs converging in the direction of the outlet end thereof, and baffling Tmeans supported at the converging ends of'said legs and disposed'transversely of the path of travel of combustion gases flowing through said chamber. 5. A checkerwork structure for usein a furnace including a plurality of vertically spaced rings ofrefractory material adapted for contact with the walls of said furnace and interposed spaced blocks of refractory material separating said rings, said rings and blocks cooperating to form a generally conically shaped chamber therein, and upwardly and inwardly inclined standards within said chamber supporting the inner ends of at least a portion of said blocks, those blocks supported by said standardsbeing adapted to slide upwardly thereon under the influence of radial expansive pressure set up therein due to increase in temperature. thereof.

6. A furnace checkerwork comprising a series of axially aligned refractory rings disposed in vertically spaced groups, spaced refractory bricks disposed between each said series and that one of said series next above it, said rings in said series above .the lowermost series being'supported on said bricks therebelow, and meansfor supporting the inner ends of said bricks comprising supporting members each having a supporting surface tapering outwardly and downwardly with respect to theaxes of said rings whereby upon expansion'of said bricks radially of said rings the inner ends of said bricksmay be forced upwardly on said supporting surfaces to relieve compressive stre'ssesin said bricks as a result of said expansion.

7-. A checkerwork for use between the inlet and'outlet of a" furnace comprising spaced serles of-refract'ory rings andalternate spaced series of refractory blocks, said blocks being arranged radially of said rings and in'spaced relation to eachcthen'the number of refractory-elements in said series progressively increasingfrom the inlet end toward the outlet end of said checkerwork whereby the heat absorbing capacity of said checkerwork progressively increases from said inlet end toward said outlctnfii '8', A checke'rwork'for use betweenv the inlet and the outlet of a furnace' comprising vertically spaced jserie's'of refractory rings and alternate vertically spaced'series'of refractory blocks, said blocksbeing arranged radially of said rings and in spajc'ed frelation to each'other, the length of said.blo cks'fin said"series of blocks increasing from the inlet end of said checkerwork toward the outlet end thereof whereby to progressively increase the battling, effect of said checkerwork from said inletend toward said outlet end.

v9'. A checkerwork for use between the inlet and the outlet of afurnace, comprising vertically spaced series of refractory. rings and alternate vertically spaced series of refractory blocks, said blocks being arranged radially of said rings and in spaced relation to each other, the number of rings in said series of rings increasing from the inlet end thereof toward the'outlet end thereof whereby to provide a checkerwork progressively increasing in heat absorbing, capacity from the inlet end thereof toward the outlet end thereof.

10. A checkerwork for use between the inlet and the outlet of a furnace, comprising vertically spaced series of refractory rings and alternate vertically spaced series-of refractory blocks, said blocks being arranged radially with respect to said rings in spaced relation to each other, the number of rings in each of said series of rings increasing from the inlet end' of said checkerwork towards the outlet end thereof, and the rings of any one of said series of-rings being arranged in'spac'ed and concentric relation with respect to each other whereby to provide a checkerwork progressively increasing in heat absorbing capacity and bafiling effect from the inlet end thereof toward the outlet end thereof.

JOHN c. CAMERON. CHARLES E. R. WEST. 

